Sandblast nozzle



Feb. 26, 1952 MARJAMA 2,587,184

SANDBLAST NOZZLE Filed May 9, 1949 A1. w/v Z. MAQ JAMA,

IN V EN TOR.

Qrrbemsy Patented Feb. 26, 1952 UNITED STATES PATENT OFFICE S-ANDBLAST NOZZLE Alvin L. Marjama, Monterey Park, Calif.

Application May 9, 1949, Serial No. 92,110

10 Claims.

This invention has to do generally with improvements in sand blast nozzles used for such various purposes as the removal of paint, corrosion or other surface coatings, or for the restoration of weathered, soiled or otherwise concealed or coated surfaces, by projecting a high velocity sand particle and air stream against the work being conditioned. Particularly the invention is concerned with a highly eflicient improved nozzle design for preventing troublesome dust formations resulting from the sand impact against many different kinds of work.

Sand blasting of various surfaces, e. g., painted, plastered or stone facings, may tend to create an objectionable dust release of the materials impacted by the sand particles. My primary object is to settle the dust immediately upon its particle formation, by creating in the projected air and sand particle stream a finely atomized dispersion of liquid in such complete uniformity of distribution as to completely blanket the dust at the surface. The invention further contemplates fogging the air and sand stream with liquid particles or vapor to a degree preventing sparking of the sand particle contact with the nozzle, and avoidance therefore of hazardous use in any combustible atmosphere. The liquid used may consist simply of water, or where it may be desirable to treat or condition simultaneously the work surface, e. g., a metallic surface subject to rusting or corrosion, I may use liquids having such compositions as rust preventatives.

Structurally the invention is directed vtothe provision on the nozzle of a mixin tip into which the liquid is taken for intimate mixture with the sand and air stream. In its particular form; the tip is shaped to contain an enlarged liquid inlet chamber, beyond which the discharge passage is reduced or constructed at or toward the point of the air stream release to the atmosphere. Preferably, the tip chamber is constructed and supplied with liquid in a manner assuring uniform distribution of the liquid about and its entrainment in the outer side of the air stream sothat liquid mist blanketing of the work surface will tend to occur sufficiently toward the outside of the blasted area as not to interfere with the normal or desired sand blast pattern.

The invention may be embodied to particular advantage in a sand blast nozzle the body of which has a hard metal lining contained within a softer metal sleeve, the latter being threaded to receive the tip section so that the water induction chamber in the tip is axially defined by the end of the body and a forwardly spaced wall through which the water-sand and liquid blast is discharged.

All the features and objects of the invention, as well as the details of an illustrative embodiment, will be fully understood from the following description of the accompanying drawing, in which:

Fig.- 1 is a general view showing the nozzle assembly and liquid supply connection in side eleva- Fig. 2 is a longitudinal sectional view of Fig. 1;

Fig. 3 is an enlarged tip end view of Fig. 1; and

Fig. 4 is an enlarged cross section on line 44 of Fig. 2.

Referring first to Fig. 1, the nozzle assembly comprises a tubular body, generally indicated at H], to which is applied, as by expansion about its inner end I M, a hose H conducting a high velocity stream of air carrying entrained sand particles. The outer end of the nozzle body l0 carries a tip l2, the details of which will presently appear, to which a liquid is supplied through the tubing l3 and valve controlled fitting I4.

As particularly illustrated in Fig. 2, the nozzle body is shown to comprise a hard, wear resisting metal lining l5, made for example of tungsten carbide, and a relatively softer steel sleeve or case IS, the outer end of which overlaps the core as at I1. The sleeve I6 is externally threaded at l8 to receive a screwed-on tubular tip l9 in axial alinement with the body bore 20,. the tip being internally threaded at 2| and having an internal diameter sufiiciently larger than the external diameter of the nozzle body, as to form about the discharge end of the latter an annular space or channel 22. Liquid is supplied from hose l3 under control of'the valved fitting l4 through the L connection 23 into the annular channel 22.

The tip l9 contains a pair of axially spaced annular members, such as washers 24 and 25 threaded into the tip and containing openings 26 and 21, the latter at least being larger than the body bore 20. Washer 25 together with washer 24 and the end of the body It] define an annular chamber 28 for reception of the liquid to be introduced to the high velocity air and sand stream, uniformly about its periphery. The washer 24 contains a circular series of uniformly .spaced openings 29, see Fig. 1, through which ly surrounding liquid contained in the chamber 28. The liquid is thus uniformly entrained and reduced to atomized particle form in and continuously about the projected sand blast stream being directed against the work. The surrounding or enveloping moisture impinges against the work surface about the central area impinged by the sand particles, all in a manner such that the moisture tends to confine and settle the dust particles since the latter must pass through the enveloping moisture to gain access to the open atmosphere. A further feature of particular importance is that with the liquid particles entrained in, but about the sand blast stream, the pattern of the latter is not appreciably affected, with the result that it becomes possible to maintain the required concentration and distribution of the projected sand particles free of interference by the surrounding liquid particles.

I claim:

1. A sand blast nozzle comprising a tubular body containing a sand and air passing bore, a removable discharge tip secured to said body, a pair of axially spaced annular members within said tip defining a chamber and containing central openings through which a high velocity stream of air and sand is projected from said hose, the rear one of said members being engaged against the end of said body and containing an opening communicating with a space in the tip surrounding the body, and means for feeding to said space, liquid passing therefrom into said chamber and the air and sand stream.

2. A sand blast nozzle comprising a tubular body containing a sand and air passing bore, a removable discharge tip secured to said body, a pair of axially spaced annular members within said tip defining a chamber and containing central openings through which a high velocity stream of air and sand is projected from said hose, the

rear one of said members being engaged against the end of said body and containing a series of circularly spaced apertures communicating with a space in the tip surrounding the body, and means for feeding to said space, liquid passing therefrom into said chamber and the air and sand stream.

3. A sand blast nozzle comprising a tubular body having a forward portion containing a chamber through the center of which a high velocity air and sand stream is projected from the body, said body having a generally transversely extending wall at the forward end of the chamber containing an opening of a transverse dimension smaller than said chamber through which the stream discharges, said chamber having an outer portion extending about the path of said stream and located directly to the rear of said Wall, said outer portion of the chamber being exposed to the stream along the major portion of its extent thereabout, and means for introducing liquid into said outer portion of the chamber so that it surrounds the air and sand stream and is entrained in the outer portion thereof, the path of the combined air, sand and liquid stream being unobstructed to radial expansion of the stream substantially directly beyond said chamber to a dimension substantially greater than said opening, and being then unobstructed to delivery of the stream onto a work surface without substantial constriction from said expanded condition.

4. A sand blast nozzle as recited in claim 3, in which the radially inner portion of said generally transverse wall forming the most restricted portion of said opening is of an axial dimension small as compared with the radial dimension of the opening to permit said expansion of the sand, air and liquid stream.

5. A sand blast nozzle as recited in claim 3, in which said outer portion of the chamber is exposed to the stream substantially entirely thereabout.

6. A sand blast nozzle as recited in claim 3, in which the forward portion of the body comprises a removable tip containing said chamber and carrying said wall.

7. A sand blast nozzle as recited in claim 3, in Which said body contains a sand and air delivery passage having a forward portion discharging said stream forwardly through the center of said chamber from a location at the rear thereof and toward said opening, said forward discharge portion of said delivery passage being of a transverse dimension smaller than said opening.

8. A sand blast nozzle as recited in claim 3, in which said liquid feeding means includes an annular space in the body rearwardly of and communicating with the chamber, and means for feeding liquid into said space for delivery longitudinally of the body into the chamber.

9. A sand blast nozzle comprising a tubular body having a forward portion containing a chamber through the center of which a high velocity air and sand stream is projected from the body, said body containing a sand and air stream delivery passage having a forward portion discharging forwardly through the center of said chamber from a location at the rear thereof, said body having a generally transversely extending annular wall at the forward end of the chamber containing a discharge opening of a transverse dimension smaller than the chamber but substantially larger than the forward portion of said passage, whereby the air and sand stream may expand radially during passage through the chamber, said chamber having an annular outer portion extending about the path of said stream and located directly to the rear of said wall, said outer portion of the chamber being exposed to the stream along substantially its entire circular extent, and means for introducing liquid into said outer portion of the chamber so that it surrounds the air and sand stream and is entrained in the outer portion thereof, the path of the combined air, sand and liquid stream being unobstructed to substantially unrestricted radial expansion of the stream substantially directly beyond said chamber, and being then unobstructed to delivery of the stream onto a work surface without constriction from said expanded condition, the radially inner portion of said transverse wall being of an axial dimension small as compared with the radial dimension of the opening.

10. A sand blast nozzle comprising a tubular body having a forward portion containing a chamber through the center of which a high velocity air and sand stream is projected from the body, said body containing a sand and air stream delivery passage having a forward portion discharging forwardly through the center of said chamber from a location at the rear thereof, said body having a generally transversely extending annular wall at the forward end of the chamber containing an opening of a transverse dimension smaller than the chamber through which the stream discharges, said wall having a substantially directly transverse rear surface extending about and adjacent said opening, said opening being at all points along its axial extent of a transverse dimension larger than said forward portion of the sand and air delivery passage to permit radial expansion of the stream during its passage through the forward portion of the body, and means for introducing liquid to said outer portion of the chamber so that it surrounds the air and sand stream and is entrained in the outer portion thereof, the path of said combined air, sand and liquid stream beyond said wall being open to passage of the stream onto a work surface without substantial constriction from the expanded dimension of said opening.

ALVIN L. MARJAMA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,376,616 Oechsle et a1 May 22, 1945 2,405,854 Ruemelin Aug. 13, 1946 2,440,334 Gerlach Apr. 2'7, 1948 2,440,643 Pettinos Apr. 27, 1948 FOREIGN PATENTS Number Country Date 560,669 France July 16, 1923 

